CVE-2026-23524
📋 TL;DR
CVE-2026-23524 is a critical deserialization vulnerability in Laravel Reverb that allows remote code execution when horizontal scaling is enabled. Attackers can exploit insecure Redis configurations to send malicious serialized data that gets executed via PHP's unserialize() function. This affects Laravel applications using Reverb versions 1.6.3 and below with REVERB_SCALING_ENABLED=true.
💻 Affected Systems
- Laravel Reverb
📦 What is this software?
Reverb by Laravel
⚠️ Risk & Real-World Impact
Worst Case
Full server compromise allowing attackers to execute arbitrary code, access sensitive data, pivot to other systems, and maintain persistent access.
Likely Case
Remote code execution leading to application takeover, data theft, and potential lateral movement within the network.
If Mitigated
Limited to denial of service or information disclosure if Redis is properly secured and network-restricted.
🎯 Exploit Status
Exploitation requires access to Redis (often unauthenticated) and knowledge of the vulnerability. The deserialization attack pattern is well-known and weaponization is likely.
🛠️ Fix & Mitigation
✅ Official Fix
Patch Version: 1.7.0
Vendor Advisory: https://github.com/laravel/reverb/security/advisories/GHSA-m27r-m6rx-mhm4
Restart Required: Yes
Instructions:
1. Update Laravel Reverb to version 1.7.0 or higher using composer: composer require laravel/reverb:^1.7.0
2. Restart the Reverb server
3. Verify the update with: composer show laravel/reverb
🔧 Temporary Workarounds
Disable Horizontal Scaling
allSet REVERB_SCALING_ENABLED=false to bypass vulnerable Redis deserialization logic
export REVERB_SCALING_ENABLED=false
Or set in .env: REVERB_SCALING_ENABLED=false
Secure Redis Configuration
allRequire Redis authentication and restrict network access
redis-cli CONFIG SET requirepass "StrongPassword123"
Edit redis.conf: requirepass StrongPassword123
Bind Redis to localhost: bind 127.0.0.1
🧯 If You Can't Patch
- Disable horizontal scaling by setting REVERB_SCALING_ENABLED=false in environment
- Implement network segmentation: restrict Redis to private network/localhost only with firewall rules
🔍 How to Verify
Check if Vulnerable:
Check Laravel Reverb version and scaling configuration: 1. Run: composer show laravel/reverb | grep versions
2. Check .env file for REVERB_SCALING_ENABLED=true
3. Verify if vulnerable if version ≤1.6.3 AND scaling enabledCheck Version:
composer show laravel/reverb | grep versionsVerify Fix Applied:
1. Confirm version is 1.7.0 or higher: composer show laravel/reverb
2. Verify the fix by checking the commit 9ec26f8ffbb701f84920dd0bb9781a1797591f1a is included📡 Detection & Monitoring
Log Indicators:
- Unusual Redis connection attempts
- PHP unserialize errors in application logs
- Unexpected process execution from Reverb
- Redis commands containing serialized PHP objects
Network Indicators:
- Unencrypted Redis traffic to Reverb servers
- Redis connections from unexpected sources
- Traffic patterns suggesting Redis data exfiltration
SIEM Query:
source="*reverb*" AND ("unserialize" OR "Redis" OR "scaling") | stats count by src_ip, dest_ip🔗 References
- https://cwe.mitre.org/data/definitions/502.html
- https://github.com/laravel/reverb/commit/9ec26f8ffbb701f84920dd0bb9781a1797591f1a
- https://github.com/laravel/reverb/releases/tag/v1.7.0
- https://github.com/laravel/reverb/security/advisories/GHSA-m27r-m6rx-mhm4
- https://laravel.com/docs/12.x/reverb#scaling
